IN-DEPTH: The wood screws CE Marking mystery, part 1

Wood timber construction has developed into a major player in the market – and the demand for the requisite wood construction screws has become very high. But the marking of these screws has been subject to a unique and opaque situation. AVVIO’s Werner Braun throws light on how this came about.

Everything began between 1990-2000 when wood screws became bigger and bigger in diameter and length. Finally, in the years around 2000, the wood construction screw successfully conquered the timber construction field. The wood construction screw gradually replaced established simple joining techniques such as the nail or the likes of DIN 571. The use of wood screws, which could be set easily and without predrilling, saved time and money. The triumphal march of the wood screw had begun. With this new connection technology in use, new application options were suddenly possible. Timber construction developed into what it is today: a future-oriented design with sustainability and great potential.

A first standardisation – the German approval with the famous “Ü”-Symbol
It quickly became clear that these new applications in structural timber construction also required the possibility of static verification for their performance in installation. The national German approval for screws known as “Deutsche Zulassung” in load-bearing timber construction was born. The first German approvals were issued in the ‘90s and the great demand started in 2000. In the middle of 2013 approximately 60 German approvals for screws were in circulation in Europe. Of those, approximately 70% were held by German companies, 16% from Austrian companies, 7% from Taiwanese, 5% from Swiss and 2% from Italian companies. Most of them were held as approval for screws as wood fasteners and for insulation and roofing systems.

The German approval regulates the usability and applicability of these screws. The basis was the building regulations of the federal states in Germany. A “Ü”-Symbol was printed on the packaging as a mark of its conformity. All quality tests within the scope of the German approvals related to the screw – a genuine pure product test combined with controlled production processes.

A Europe-wide standard – but the first CE marking cannot be implemented by manufacturers
In 2002, the European Committee for Standardisation (CEN) began drafting a European standard to regulate these fasteners for load-bearing timber construction throughout Europe. EN 14592 was intended to regulate these construction products. In 2008, this standard came into force as EN 14592:2008 and regulated the CE marking of screws in structural timber construction from August 2010. However, due to considerable deficiencies in this standard, CE marking for all existing products was simply not possible at this time. An example of this was the specification in EN 14592 according to 6.3.2, which prescribes other steel material qualities for production than were usual in practice. The requirements for CE marking laid down in EN 14592 could not be implemented in practice.

The world of ETAs is born
Well-known manufacturers came together and explained in a joint letter to their customers that for various reasons no CE marking of the screws is feasible, despite it being required by European law. A solution was feverishly sought. One solution was to obtain their own approval in the form of a European Technical Approval (ETA). However, this required a guideline which was published in the form of CUAP 06.03/08 in December 2010. From this point on it was possible to apply for an ETA at the EOTA offices in Europe. Already in 2011, the first ETAs for screws in
Germany were issued. Soon thereafter many more followed. On the basis of these ETAs a CE marking was now possible under the valid Construction Products Directive (CPD) 89/106/EEC.

Innovations on several fronts and a confusion of markings
Only when the version EN 14592:2008+A1:2012 came into force on 1 March 2013 CE marking was possible according to a harmonised standard.

However, a further change took place with the replacement of the Construction Products Directive (CPD) 89/106/EEC by the Construction Products Regulation (CPR) 305/2011/EU on 1 July 2013. With this replacement, further extensive changes in connection with basic regulations came into force.

For example, the former European Technical Approval became a European Technical Assessment. The previous guideline CUAP was to be replaced by an EAD – but this EAD was missing at the time of the changeover. From this point on it was no longer possible to apply for an ETA or to change existing ETAs, because a basic EAD was missing. The EAD was only published in 2017 and from this point on it was again possible to change ETAs or apply for new ones.

From the beginning, the “Ü”-mark consisted of the German approval. This had to be used additionally for market access in Germany. According to the European Court of Justice (EuGH), this restriction for Germany was not admissible and after the judgement of 16 October 2014 this mark had to disappear.

And so, it came that today more than 60 valid ETAs are in circulation in Europe and countless CE markings according to EN 14592:2008 for screws used in load-bearing timber constructions.

EN 14592:2012 – CE Marking of Construction Products – Truth and myth
Perhaps because of this eventful history, a common misunderstanding persists, namely that there would be a general CE labelling obligation for every fastener that is to be sold in Europe.

What is true, is that an obligation to CE marking can be derived from various European directives, which by now cover a wide range of products (e.g. Low Voltage Directive (LVD) 2006/95/EC, Medical Devices Directive (MDD) 93/42/EEC, Machinery Directive (MD) 2006/42/EC or Electromagnetic Compatibility Directive (EMC) 2004/108/EC), to name a few). For Construction Products it was the above mentioned Construction Product Directive (CPD) 89/106/EEC, which is now replaced by the Construction Product Regulation (CPR) 305/2011/EU.

The CPR generally stipulates that construction products which are covered by a harmonized standard must be CE marked. As there are over 600 of harmonised standards issued by now, it can by quite tricky to clarify that question though. But even if the right standard is found, to decide whether it applies to a specific product and its specific application often requires deep knowledge of the relevant provisions.

Figure 1 illustrates such a process to check, if a fastener must be CE marked or not.

Once established that a CE marking based on a harmonised standard is necessary, it becomes a legal prerequisite for placing the product on the market in the European Economic Area. The CE mark is therefore sometimes referred to as a “product passport” necessary for a product to enter the European Economic Area.

Another important clarification concerns the fact that the CE mark is not a quality seal. With the CE mark the manufacturer only guarantees the conformity of a product with the declared performances and the compliance with all regulations for the CE marking.

In the case of CE marking, however, the manufacturer has important obligations:
• Preparation of a declaration of performance (DoP) for each product that is made available on the market (in printed or electronic form).
• Provision of the declaration of performance (DoP) in the language of each country in which the product is provided.
• Attachment of the CE marking to the construction product (or packaging)
• Responsibility for the conformity of the construction product with the declared performance
• Set up and conduction of a factory production control (FPC)

The main difference between an ETA (approval) issued under the Construction Products Directive (CPD) and an ETA (assessment) issued under the Regulation (CPR) is the following:
• In the CPD context, the ETA (approval) was a technical assessment of the fitness for use of a construction product for an intended use. All relevant characteristics and aspects for the use of the product were assessed, amongst others packaging, storage, transport, installation, and maintenance.
• In the CPR context, the ETA (assessment) is based on an agreement between the manufacturer and the Technical Assessment Body (TAB) concerning those characteristics for which the manufacturer wishes to declare the performance and which might be relevant for the intended use. It is the documented assessment of the performance of a construction product as it has just been manufactured, in relation to its essential characteristics.

About the author, Werner Braun:Werner is a true fastener aficionado and he runs AVVIO, an Austrian based technical laboratory specialised on services around fasteners. AVVIO provides a wide range of testing and consulting services in regards of ETA and CE marking and developed its own quality seal AV24. Readers are welcome to get in contact and send their feedback to lab@avvio.at or visit www.avvio.at or www.av24.at

Read more about the past and future of CE Marking of wood screws in April’s Torque Magazine. Don’t get the magazine? Subscribe here.